Basic Experiment of Etching of the Ceramic Surface by Electrolytic/Electro-Discharge Composit Machining Method

采用电解液电解加工的方法，对陶瓷材料表面的刻蚀进行了实验研究。将氧化铝或SiC陶瓷试样分别浸泡在0.01 ~ 1 mol/l NaOH、HCl、H_3PO_4、NaH_2PO_4、Na_2HPO_4和Na_3PO_4溶液中。采用0.8 mm钨丝作为工具电极，将其压在试样上。熔坑的最大穿透深度和形状取决于：(1)电解液的种类及其浓度；(2)工具电极与对电极之间的外加电压；(3)电极的极性。工具电极为负时的弹坑比工具电极为正时的弹坑深。观察到两种类型的陨石坑。深坑的最深部分对应于坑的中心（I型），浅坑的最深部分对应于坑的边缘（II型）。结果表明：(1)存在于氧化铝晶粒晶界处的少量氧化铝陶瓷在初期受到攻击，随后氧化铝晶粒断裂；(2)氧化铝在Na_2HPO_4或Na_3PO_4溶液中均有较好的效果。结果表明：(1)SiC在0.01或0.1 mol/l NaOH溶液中均能得到较好的效果；(2)SiC晶粒本身在NaOH溶液中受到侵蚀。

An experimental investigation of the etching of the surface of ceramic materials was carried out by means of electro-discharge machining method in electrolyte solutions. Specimens of alumina or SiC ceramics were immersed in 0.01 - 1 mol/l NaOH, HCl, H_3PO_4, NaH_2PO_4, Na_2HPO_4 and Na_3PO_4 solutions. 0.8 mm tungsten wire was used as a tool electrode and it was pressed to the specimen.The maximum penetration depth and shape of crater depend on (1) kinds of electrolyte and its concentration, (2) applied voltage between tool electrode and counter electrode and (3) polarity of it. Craters in case of negative tool electrode were deeper than those in case of positive tool electrode. Two types of craters were observed. The deepest portion corresponded to the center of crater (TYpe I) in case of the deep crater and corresponded to the edge of crater (TYpe II) in case of the shallow crater. It was observed that (1) minor composition of alumina ceramic, which existed at the grain boundary of alumina grain, was attacked at the early stage and then alumina grain broke away, and that (2) alumina in Na_2HPO_4 or Na_3PO_4 solutions gave the good results. It was also observed that (1) SiC in 0.01 or 0.1 mol/l NaOH soultion gave the good results and that (2) SiC grain itself was attacked in these solutions.